Abstract: A linear actuator includes a motor, a movable unit, and a stroke control unit. The motor includes a spindle. The movable unit includes a worm gear and a rotary shaft. The worm is provided with annular spiral or helix teeth. The stroke control unit includes at least one transmission member and at least one micro switch. The at least one transmission member is engaged with and driven by the spiral or the helix teeth of the movable unit for synchronical rotation to activating or deactivating the micro switch. In this way, the linear actuator is simplified in structure and reduced in volume.